Laser directed thermometer

ABSTRACT

Method and apparatus are provided for visibly outlining the energy zone to be measured by a radiometer. The method comprises the steps of providing a laser sighting device on the radiometer adapted to emit more than two laser beams against a surface whose temperature is to be measured and positioning said laser beams about the energy zone to outline said energy zone. The apparatus comprises a laser sighting device adapted to emit more than two laser beams against the surface and means to position said laser beams about the energy zone to outline said energy zone. The laser beams may be rotated about the periphery of the energy zone. The laser beams may be rotated about the periphery of the energy zone. In another embodiment, a pair of laser beams are projected on opposite sides of the energy zone. The laser beams may be further pulsed on and off in a synchronized manner so as to cause a series of intermittent lines to outline the energy zone. Such an embodiment improves the efficiency of the laser and results in brighter laser beams being projected. In yet another embodiment, a primary laser beam is passed through or over a beam splitter or a diffraction grating so as to be formed into a plurality of secondary beams which form, where they strike the target, a pattern which defines an energy zone area of the target to be investigated with the radiometer. Two or more embodiments may be used together. A diffraction device such as a grating may be used to form multiple beams. In a further embodiment, additionally laser beams are directed axially so as to illuminate the center or a central are of the energy zone.

RELATED APPLICATIONS

[0001] This is a continuation-in-part application of both pending U.S.patent application Ser. No. 08/764,659 filed on Dec. 11, 1996 and Ser.No. 08/617,265 filed on Mar. 18, 1996 in the names of Milton B.Hollander and W. Earl McKinley for Method and Apparatus for measuringTemperature Using Infrared Techniques, the latter of which, is acontinuation-in-part application of U.S. application Ser. No. 08,348,978field on Nov. 28, 1994, now U.S. Pat. No. 5,524,984 which in turn was acontinuation-in-part application of then copending U.S. patentapplication Ser. No. 08/121,916 filed Sep. 17, 1993, now issued as U.S.Pat. No. 5,368,392, on Nov. 29, 1994.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to a method and apparatusfor more accurately measuring the temperature of a surface usinginfrared measurement techniques and, more particularly, to such a methodand apparatus which utilizes a laser sighting device which is adapted toproject at least a circumscribing laser sighting beam or beams for moreclearly defining the periphery of the energy zone from which thetemperature is measured. Generally speaking, this has been accomplishedby directing the laser beam about the periphery of the energy zone; bythe use of three or more stationary laser beams which are focused on theperiphery of the energy zone; or by the use of a controlled single laserbeam directed towards three or more predetermined locations on theperiphery of the energy zone. In the alternative embodiment, a singlelaser beam may be rotated around the periphery of the energy zone using,for example, slip rings. In another embodiment, the single rotatinglaser may be pulsed on and off in a synchronized manner in order toproduce a series of intermittent lines outlining the energy zone, thusincreasing the efficiency of the laser by concentrating its totalwattage in a smaller area, causing a brighter beam. Further, thecircumscribing beam or beams may be used in conjunction with anadditional beam directed at and defining a central spot, or largercentral area, of the energy zone.

[0004] In yet another method and embodiment, at least one laser beam issubdivided by passing it through a diffraction grating, for example,into a plurality of three or more subdivision beams which can form apattern of illuminated spot areas on a target whose energy zone is to beinvestigated with a radiometer. Herein “a plurality” means three ormore, e.g. six or twelve.

[0005] 2. Description of the Prior Art

[0006] Remote infrared temperature measuring devices (commonly referredto as infrared pyrometers or radiometers) have been used for many yearsto measure the temperature of a surface from a remote location. Theirprinciple of operation is well known. All surfaces at a temperatureabove absolute zero emit heat in the form of radiated energy. Thisradiated energy is created by molecular motion which produceselectromagnetic waves. Thus, some of the energy in the material isradiated in straight lines away from the surface of the material. Manyinfrared radiometers use optical reflection and/or refraction principlesto capture the radiated energy from a given surface. The infraredradiation is focused upon a detector, analyzed and, using well knowntechniques, the surface energy is collected, processed and thetemperature is calculated and displayed on an appropriate display.

[0007] Examples of such infrared radiometers are illustrated at pagesJ-1 through J-42 of the Omega Engineering Handbook, Volume 2B. See,also, U.S. Pat. No. 4,417,822 which issued to Alexander Stein et al. onNov. 29, 2983 for a Laser Radiometer; U.S. Pat. No. 4,527,896 whichissued to Keikhosrow Irani et al. on Jul. 9, 1985 for an InfraredTransducer-Transmitter for Non-Contact Temperature Measurement; and U.S.Pat. No. 5,169,235 which issued to Hitoshi Tominaga et al. for RadiationType Thermometer on Dec. 8, 1992. Also see Baker, Ryder and Baker,Volume II, Temperature Measurement in Engineering, Omega Press, 1975,Chapters 4 and 5.

[0008] When using such radiometers to measure surface temperature, theinstrument is aimed at a target or “spot” within the energy zone on thesurface on which the measurement is to be taken. The radiometer receivesthe emitted radiation through the optical system and is focused upon aninfrared sensitive detector which generates a signal which is internallyprocessed and converted into a temperature reading which is displayed.

[0009] The precise location of the energy zone on the surface as well asits size are extremely important to insure accuracy and reliability ofthe resultant measurement. It will be readily appreciated that the fieldof view of the optical systems of such radiometers is such that thediameter of the energy zone increases directly with the distance to thetarget. The typical energy zone of such radiometers is defined as where90% of the energy focused upon the detector is found. Heretofore, therehave been no means of accurately determining the perimeter of the actualenergy zone unless it is approximated by the use of a “distance totarget table” or by actual physical measurement.

[0010] Target size and distance are critical to the accuracy of mostinfrared thermometers. Every infrared instrument has a field of view(FOV), an angle of view in which it will average all the temperatureswhich it sees. Field of view is described either by its angle or by adistance to size ratio (D:S). If the D:S=20:1, and if the distance tothe object divided by the diameter of the object is exactly 20, then theobject exactly fills the instrument's field of view. A D:S ratio of 60:1equals a field of view of 1 degree.

[0011] Since most infrared thermometers have fixed-focus optics, theminimum measurement spot occurs at the specified focal distance.Typically, if an instrument has fixed-focus optics with a 120:1 D:Sratio and a focal length of 60″ the minimum spot (resolution) theinstrument can achieve is 60 divided by 120, or 0.5″ at a distance of60″ from the instrument. This is significant when the size of the objectis close to the minimum spot the instrument can measure.

[0012] Most general-purpose infrared thermometers use a focal distanceof between 20″ and 60″ (50 and 150 cm); special close-focus instrumentsuse a 0.5″ to 12″ focal distance. See page Z54 and Z55, volume 28, TheOmega Engineering Handbook, Vol. 28. In order to render such devicesmore accurate, laser beam sighting devices have been used to target theprecise center of the energy zone. See, for example, pages C1-10 throughC1-12 of The Omega Temperature Handbook, Vol. 27. Various sightingdevices such as scopes with cross hairs have also been used to identifythe center of the energy zone to be measured. See, for example, PagesC1-10 through C1-21 of The Omega Temperature Handbook, Vol. 27.

[0013] The use of a laser to pinpoint only the center of the energy zonedoes not, however, provide the user with an accurate definition of theactual energy zone from which the measurement is being taken. Thisinability frequently results in inaccurate readings. For example, incases where the area from which radiation emits is smaller than thetarget diameter limitation (too far from or too small a target),inaccurate readings will occur.

[0014] One method used to determine the distance to the target is toemploy an infrared distance detector or a Doppler effect distancedetector or a split image detector similar to that used in photography.However, the exact size of the energy zone must still be known if one isto have any degree of certainty as to the actual area of the surfacebeing measured. This is particularly true if the energy zone is toosmall or the surface which the energy zone encompasses is irregular inshape. In the case where the surface does not fill the entire energyzone area, the readings will be low and, thus, in error.

[0015] Similarly, if the surface is irregularly shaped, the readingswill also be in error since part of the object would be missing from theactual energy zone being measured.

[0016] Thus, the use of a single laser beam only to the apparent centerof the energy zone does not insure complete accuracy since the user ofthe radiometer does not know specifically the boundaries of the energyzone being measured.

[0017] As will be appreciated, none of the prior art recognizes thisinherent problem o offers a solution to the problems created thereby.

[0018] Proposals have ben made in the prior art for indicating an energyzone area of a target surface by means visible to the eye of the target.

[0019] A first kind of such indication utilizes multi-spectral light, asevidenced for example in the Japanese Publication No. S57-22521 whichteaches the use of an incandescent light source to outline an energyzone at the target. Japanese Publication No. 62-12848 suggests a similaruse of multi-spectral light to outline an energy zone at the target.Reference is made to Japanese case JP 63-145928.

[0020] Further, U.S. Pat. No. 4,494,881 EVEREST also suggests using amulti-spectral light source together with a beam splitter arrangementwhich permits the infra-red received beam and the multi-spectral lightto utilize the same optical arrangement. EVEREST teaches the use of avisible light source such as an incandescent lamp or strobe light whichis projected against the target surface, the temperature of which is tobe measured. This adds additional energy to the same energy zone wherethe temperature measurement is to be taken, and this destroys accuracy.When EVEREST uses a beam splitter, the incandescent light beam causesthe beam splitter to act as a radiator of infrared energy. When EVERESTuses a Fresnel lens, the light tends to elevate the temperature of theFresnel lens, which in turn reflects back to the infra-red detector.

[0021] This manner of indication, utilizing incoherent multi-spectrallight, has the disadvantage amongst others that the multi-spectral lightitself has a heat factor which can cause incorrect reading by the energydetecting means of the apparatus.

[0022] A laser is Light Amplification by Stimulated Emission ofRadiation. This device was invented in 1960 to produce an intense lightbeam with a high degree of coherence. Atoms in the material emit inphase. Laser light is used in holography. A light beam is coherent whenall component waves have the same phase. A laser emits coherent light,but ordinary electric incandescent light is incoherent in which atomsvibrate independently.

[0023] It is not possible simply to substitute a laser for anincandescent light source, because the incandescent beam is incoherentin nature, so that when projected parallel and in close proximity to theboundaries of the invisible infra-red zone, incandescent light insidethe infra-red zone is reflected as heat energy. Moving the incandescentbeam well away from the infra-red zone clearly does not permit accuratedelineation of the target zone.

[0024] A second kind of energy zone indicator utilizes coherent laserlight, as evidenced for example in U.S. Pat. No. 4,315,150 of DERRINGER,which is directed to a targeted infrared thermometer in which a laser isprovided to identify the focal point, i.e., the center, of the energyzone, but there is nothing in DERRINGER to suggest causing more than twolaser beams to outline the energy zone.

[0025] U.S. Pat. No. 5,085,525 BARTOSIAK ET AL teaches use of a laserbeam to provide a continuous or interrupted line across a target zone tobe investigated, but there is no suggestion to outline a target zone,nor to indicate a central point or central area of the target zone.

[0026] German patent publications of interest include:

[0027] DE-38 03 464

[0028] DE-36 07 679 to a laser sighting device.

[0029] DE-32 13 955 to a beam splitter and to dual laser beams toindicate position and diameter of the energy zone

[0030] All of the above noted prior art is hereby incorporated into thiscase by reference thereto.

SUMMARY OF THE INVENTION

[0031] Against the foregoing background, it is a primary object of thepresent invention to provide a method and apparatus for measuring thetemperature of a surface using infrared techniques.

[0032] It is another object of the present invention to provide such amethod and apparatus which provides more accurate measurement of thesurface temperature than provided by the use of techniques heretoforeemployed.

[0033] It is yet another object of the present invention to provide sucha method and apparatus which permits the user visually to identify thelocation, size nd temperature of the energy zone on the surface to bemeasured.

[0034] It is still yet another object of the present invention toprovide such method and apparatus which employs a heat detector and alaser beam or beams for clearly outlining the periphery of the energyzone of the surface.

[0035] It is a still further object of the present invention to providea method and apparatus which permits the use of a single laser beamwhich is subdivided by passing it through, or over, a beam splitter,holographic element or a diffraction grating, thereby to form aplurality of three or more subdivision beams which provide a patternwhere they strike a target whose energy zone is to be investigated.

[0036] It is still further object of the invention to provide a methodand apparatus which utilizes not only a beam or beams for outlining theenergy zone, but also an additional beam or beams directed at andilluminating an axial central spot, or larger central area, of theenergy zone.

[0037] For the accomplishment of the foregoing objects and advantages,the present invention, in brief summary, comprises a method andapparatus for visibly outlining the energy zone to be measured by aradiometer. The method comprises the steps of providing a radiometerwith a detector and a laser sighting device adapted to emit at least onelaser beam against a surface whose temperature is to be measured andcontrolling said laser beam towards and about the energy zone to outlinevisibly said energy zone. The beam is controlled in such a fashion thatit is directed to three or more predetermined points of the target zone.This can be done mechanically or electrically.

[0038] Another embodiment of this invention employs a plurality of threeor more laser beams to describe the outline and optionally also thecenter of the energy zone either by splitting the laser beam into anumber of points through the use of optical fibres or beam splitters ora diffraction device or the use of a plurality of lasers. One embodimentof the apparatus comprises a laser sighting device adapted to emit atleast one laser beam against the surface and means to rotate said laserbeam about the energy zone to outline visibly said energy zone. Thisrotation can be by steps or continuous motion.

[0039] Another embodiment consists of two or more stationary beamsdirected to define the energy zone. The three or more laser beams couldeach be derived from a dedicated laser to each beam or by means of beamsplitters. This can be accomplished by mirrors, optics, a diffractiongrating, and fibre optics.

[0040] Another embodiment consists of a laser beam splitting device thatemits one laser beam which is split into a plurality of three or morebeams, by a diffraction grating, for example, to outline the energy zoneand optionally to indicate a central spot or larger central area of theenergy zone.

[0041] In a still further embodiment, the temperature measurement devicecomprises a detector for receiving the heat radiation from a measuringpoint or zone of the object under examination. Integral to the equipmentis a direction finder, i.e. a sighting device using a laser beam as thelight source and incorporating a diffractive optic, i.e. a holographiccomponent such as a diffraction grating, or a beam splitter, with whichthe light intensity distribution is also shown and the position and sizeof the heat source is indicated. The marker system relates to apredetermined percentage, e.g. 90%, of the energy of the radiated heat.

[0042] The method includes visually outlining and identifying theperimeter of the energy zone by projecting more than two laser beams tothe edge of the 90% energy zone to mark out the limits of the surfacearea under investigation, for example, by a series of dots or spotswhich form a pattern.

[0043] Two or more embodiments may be used together or alternately.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The foregoing and still other objects and advantages of thepresent invention will be more apparent from the detailed explanation ofthe preferred embodiments of the invention in connection with theaccompanying drawings, wherein:

[0045]FIG. 1 is a schematic illustration of the prior art type ofradiometers using laser sighting devices;

[0046]FIG. 2 is a schematic illustration of one embodiment of thepresent invention in which the laser beam is circumscribing the targetzone using a mirror;

[0047]FIGS. 2A and 2B illustrate the manner in which the laser beam isrelocated in stepped fashion to identify the energy zone;

[0048]FIG. 3 is schematic illustration of an alternative embodiment ofthe present invention in which the laser is pivoted about a pivot pointby the use of mechanical motive means;

[0049]FIG. 4 is a schematic illustration of another alternativeembodiment of the present invention in which the laser is directedthrough a magnetic field to identify the target zone;

[0050]FIG. 5 is a schematic illustration of another alternativeembodiment of the present invention in which a number of individuallaser beams are projected so as to define the energy zone beingmeasured;

[0051]FIG. 6 is a schematic illustration of another alternativeembodiment of the present invention in which the laser is mechanicallypivoted;

[0052]FIG. 7 schematically illustrates the positioning of fiber opticsto create a pattern of the target zone with the laser beam;

[0053]FIG. 8 is a detailed sectional view of another alternativeembodiment of the present invention in which the laser is mechanicallypivoted about the detector;

[0054] FIGS. 9A-C illustrate alternative configurations of the outlineswhich can be projected using the apparatus of the present invention;

[0055]FIG. 10 is a schematic illustration of an embodiment of theinvention wherein the laser is divided into a plurality of laser beamsdefining the energy zone by the use of optical fibres.

[0056]FIG. 11 is a cross sectional side view of a laser sighting devicewhich may be used in conjunction with a radiometer in which the laser isrotated using slip rings;

[0057]FIG. 12 is a side view illustrating a modified version of thelaser sighting device of FIG. 11 with the sighting device mounted on aninfrared detector;

[0058]FIG. 13 is a side view illustrating still another modified versionof the laser sighting device of the present invention;

[0059]FIG. 14 is a side view of yet another embodiment of the inventionin which the laser sighting device utilizes twin laser beams provided onopposite sides of an infrared detector;

[0060]FIG. 15 is a front view of the embodiment of FIG. 14;

[0061]FIG. 16 is a top view of the embodiment of FIGS. 14-15;

[0062]FIG. 17 illustrates the intermittent lines formed by a laser whichis pulsed on and off in a synchronized manner;

[0063]FIG. 18 is an illustration in partial section of a preferredembodiment of the invention in which the laser sighting device utilizesa single laser beam which is divided and spread into a plurality ofindividual beams by means of a diffraction grating;

[0064]FIG. 19 is a diagram to show a pattern of dots of laser light,formed on a target area, as a result of impingement of the individualbeams resulting from sub-division of the single beam of the laser;

[0065]FIG. 20 is a diagram to show a modification wherein the radiometeris arranged on the axis of the laser beam.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] Traditionally, prior art radiometers have long employed lasersighting devices and direction finders to assist in the proper aim andalignment of the instrument. FIG. 1 illustrates and direction findersthe operation of traditional, prior art, hand held radiometers. Such aradiometer, referred to generally by reference numeral 10, includes alaser sight scope 12 which emits a laser beam 14 to a spot or target 18on the surface 20 whose temperature is to be measured. This spot 18 islocated in the center of the energy zone “E” which is to be measured bythe radiometer 10. The radiometer 10 includes a detector 16 which isconnected to conventional internal circuitry and display means (notshown) for conversion, calculation and display of the temperature of thesurface 20 calculated indirectly from the energy radiated from thesurface within the energy zone E. Such energy is radiated in straightlines in all directions away from the surface 20 and captured with thedetector 16 on the radiometer 10. Using infrared radiation principles,the radiometer is thus able to capture and measure the infrared energyin the energy zone E and to display the surface temperature thereof.

[0067] The actual size and shape of the energy zone E is determined bythe optics of the radiometer and the distance between the radiometer andthe target. Each radiometer has a defined angle of vision or “Field ofview” which is typically identified in the instrument's specificationsheet. The size of the energy zone E is predetermined when the field ofview is known in conjunction with the distance to the target. Obviously,the further the radiometer is held from the target (i.e., the greaterthe distance), the larger the energy zone E.

[0068] This can be expressed in a “distance to spot size zone”. Forexample, with a “distance to spot size zone” of 40:1 the periphery ofthe energy zone would have a 1″ diameter at a distance of 40″ or, at adistance of 20″ the diameter of the energy zone would be ½″. Themanufacturer of the pyrometer usually provides field of view diagramsfor determining the energy zone at specific distances.

[0069] As can readily be appreciated, however, such laser aiming devicesare merely able to identify the center of the energy zone being measuredand not the outer periphery, as distinct from the diameter, of theactual energy zone from which the measurement is being taken. Thefurther away from the surface the radiometer 10 is positioned, thelarger the energy zone E. Thus, depending upon the size andconfiguration of the surface 20, the actual energy zone E may,conceivably, include irregular shaped portions of the surface 20 or evenextend beyond the edges of the surface. Of course, in such instances,the resultant measured temperature would be inaccurate. Without knowingthe outer perimeter of such energy zone E, the user of the radiometer 10would have no knowledge of such fact and the resultant readings could beinaccurate.

[0070] The present invention provides a means for visibility definingthe energy zone E so that the user of the radiometer 10 can observe theactual energy zone being measured to determine where it falls relativeto the surface being measured. In the various embodiments of thisinvention, a fine laser line or lines is projected against the surfacebeing measured and such line or lines is positioned so as to encompassthe periphery of the energy zone E. Of a rotating laser beam isemployed, positioning can be effected, alternatively by moving eitherthe laser itself or the laser beam emitted from the laser or from alaser beam splitter.

[0071] If the perimeter of the energy zone E cold be identified on theobject by the movement of the laser beam in a path about thecircumference of the energy zone E, the user would be able quickly andaccurately to determine if the energy zone from which the measurementwas being taken was fully on the surface to be measured and whether itssurface was of the type which would provide an otherwise accuratemeasurement.

[0072] The periphery of the energy zone E is identified as a function ofthe stated “field of view” of the particular radiometer as identified inits specifications and the distance between the radiometer and thetarget. Identification of the size and shape of the energy zone iseasily done using conventional mathematical formulae. Once identified,the laser beams are then projected about the periphery of the energyzone E in accordance with the methods and apparatus hereinafterdescribed. One simple “aiming” approach is to project the laser beam atthe same angle as the field of view of the radiometer emanating from thesame axis or, alternatively, by mechanically adjusting the laser beamangle in accordance with the “distance to spot size ratio” calculations.In either event, the periphery of the energy zone E would be identifiedby the laser beams.

[0073]FIG. 2 illustrates a first embodiment of the present invention inwhich the laser aiming device 12 emits a laser beam 14 which is aimed ata mirrored surface 30 which is positioned in front of the laser beam 14.The mirror 30 is rotated using motive means 32 so as to rotate the beamin a circular fashion to define the energy zone E on the surface beingmeasured. Alternatively, the mirror 30 can be rotated by vibratory meansor by the application of a magnetic field (not shown). Rotation of themirror 30 should be a refraction angle which corresponds to the 90%energy zone E thereby permitting the laser beam 14 to rotate about theperiphery of the energy zone E and thereby making it visible to the userof the radiometer 10.

[0074] It should be appreciated that the laser aiming device 12 may bean integral part of the radiometer 10 or, alternatively, a separate unitthat may be mounted on or near the radiometer 10.

[0075] Alternatively, a prism can be used in place of the mirror 30 withpredetermined angles to cause the prism to function as the reflectingmirror surface and, thereby, direct the laser beam about the perimeterof the energy zone.

[0076]FIGS. 2A and 2B illustrate the manner in which laser beams can beused to outline the energy zone E on the surface to be measured. It isimportant that rotation of the beam 14 be carefully controlled so thatrotation is at a speed which can be visually followed. This will permitfull beam intensity. As illustrated in FIGS. 2A and 2B, the laser beamis rotated about the energy zone E through a series of steps with thelaser beam being permitted to remain in each step for at least onehundredth of a second before moving to its next position. This isaccomplished by creating a plurality of steps E-1, E-2, etc., around theenergy zone E. The laser beam 114 would stop at each step for thepredetermined period of time to permit the beam to be observed beforemoving to the next step.

[0077]FIG. 3 illustrates another embodiment of the present invention inwhich the laser 112 itself is rotated or displaced so as to scribe acircle or other closed figure which defines the energy zone E bymechanically pivoting the laser 112 about pivot point 120 using motivemeans 132. Alternatively, the laser 112 can be rotated by a vibratorymeans (not shown) or by the application of a magnetic field (not shown).Rotation of the laser 112 should, however, be at a refraction anglewhich corresponds to the 90% energy zone E thereby permitting the laserbeam 114 to rotate about the periphery of the energy zone E to make itvisible to the user of the radiometer 10.

[0078] In FIG. 4, the laser 212 is rotated about a pivot point 220 bythe application of a magnetic field 225 so as cause the emission of thelaser beam 214 around the periphery of the 90% energy zone E to make thebeam visible to the user of the radiometer 10. In such embodiment, means(not shown) are provided for modifying the magnetic field 225 tocorrespond to the 90% energy zone so as to permit the laser to berotated accordingly.

[0079] In FIG. 5, the laser 312 has at least two components 312A and312B which produce at least two individual laser beams 314A and 314Babout the detector 316. These at lest two individual beams 314A and 314Bare directed to the surface 320 being measured at the perimeter of theenergy zone E rather than at the center of the energy zone E. Throughthe use of a number greater than two of such laser beams, thesignificant energy zone E becomes clearly identified rather than merelythe center of the E zone. If desired individual lasers can be used orlaser splitting devices can be used to split a single laser beam. Adiffraction device such as a grating or holographic component may beused to form multiple beams. Two lasers may be adapted to project a pairof laser beams on different sides of said energy zone.

[0080]FIG. 6 illustrates yet another embodiment of the present inventionin which the laser 412 is mechanically pivoted in a circular fashionaround the detector 416 so as to emit a laser beam 414 in a circularpath on the surface (not shown) thereby defining the energy zone E.Laser 412 is pivotally mounted on pivot bearing 420 provided onconnecting arm 421. Arm 421 is mounted on pivot bearing 424 which isrotated by motor 422. In such a manner, the laser beam 414 emitted fromthe laser 412 rotates about and outlines the energy zone E on thesurface from which the temperature is being measured.

[0081] The rotation of the laser beam may be effected using beamsplitter or fiber optic techniques as shown in FIG. 7 in which the laserbeam is projected through fiber optic means 501. In such manner, thebeams fan out from the laser source and encircle and thereby define theenergy zone E. By the use of a sufficient number of fiber optics, onecan outline the circumference of the target area E with a light ring orby a ring of dots. This can be accomplished by as few as two fibers 501positioned 180 degrees apart since the pick up pattern would becircular. Further fiber optic means may serve to direct a laser beamonto a central spot, or larger central area, of the energy zone.

[0082]FIG. 8 illustrates still another means of effecting rotation ofthe laser beam 614 emitted from laser 612. In this manner, the laserbeam 614 is directed against a rotating flat surface mirror 630 where itis reflected against a plated plastic cone mirror 631. The reflectedbeam is then projected to the surface and defines the perimeter of theenergy zone E. The flat mirror 630 is driven by motor 622. In suchmanner, the laser beam 614 rotates about the circumference of the energyzone E on the surface being measured. The mirrors are positioned at suchan angle that the laser projection is at the same angle as the infrareddetector pickup angle.

[0083] It will, of course, be appreciated that the energy zones E mayassume configurations other than the circular configuration shown inFIGS. 1-8. FIGS. 9A-C illustrate alternative square (FIG. 9A),rectangular (FIG. 9B), and triangular (FIG. 9C) configurations for thelight patterns which may be accomplished using the means of the presentinvention. A closed configuration is preferred. This may include threeor more dots or spots.

[0084]FIG. 10 illustrates a method for defining the energy zone where acircular configuration can be accomplished without rotation of the laserbeam wherein a plurality of fixed optical fibers positioned to project anumber of spots is employed. In this figure, a fixed laser 712 projectsa beam 713 which is split into a plurality of beams 714 by a bundle ofoptical fibers 715 in order to project a pattern 716 onto the surfacedefining the energy zone E. Additional configurations may also be used,if desired. A diffraction means will also produce a pattern.

[0085] Referring to FIG. 10, the means for projecting a plurality oflaser beams (the bundle 715) will likewise include optical fibersarranged to project a laser beam axially so as to cause the plurality oflaser beams to identify and define both the center and the periphery ofthe energy zone, e.g. by providing a single center spot or largercentral area on the surface to be measured.

[0086] FIGS. 11-12 illustrate further embodiments of the presentinvention in which the laser is adapted to be rotated by the use of sliprings and counter weights. For example, FIG. 11 illustrates one lasersighting device 1000. Laser sighting device 1000 can be provided as anintegral unit in combination with an infrared detector (not shown) or,alternatively, may be self contained as a removable sighting devicewhich can be attached to and removed from infrared detectors.

[0087] The laser sighting device 1000 of FIG. 11 includes a laser 1012powered by power source 1018 which projects a laser beam 1014 againsttarget. The laser 1012 is pivotally mounted about pivot 1020. Motor 1021is provided for powering the sighting device and causing the laser 1012to rotate. An external switch (not shown) may be provided to turn themotor 1021 on and off and, as such, the rotation of the laser 1012.Upper and lower screw adjustments of 1013 and 1011, respectively, areprovided for controlling the position of the laser 1012 and, moreimportantly, the direction of the laser beam 1014. Upper screwadjustment 1013 is adapted to be used during non-rotation while lowerscrew adjustment 1011 issued during rotation of the laser 1012.

[0088] The laser 1012 is powered with power source 1018. Slip rings 1016are provided to facilitate rotation of the laser 1012. Upper and lowercounterweights 1015A and 1015B, respectively are provided above andbelow the laser 1012 and a return spring 1019 is also provided.

[0089] The laser 1012 of the sighting device 1000 in FIG. 11 is adaptedto rotate about the pivot 1020 when driven by the motor 1021. Thus, thelaser 1012 is able to project a laser beam 1014 with a circle-typepattern against a target (not shown). During rotation, centrifugal forcewill act upon the counterweights 1015A and 1015B causing the laser 1012to tilt. The angle at which it tilts can be controlled by the screwadjustment 1013 and 1011. The angle is adjusted to correspond to theinfrared detector field of the infrared detector in which the sightingdevice is used. The laser beam 1014 will then follow the periphery ofthe target zone of the infrared detector (not shown). Once the motor1021 is turned off, the return spring 1019 will cause the laser 1012 tocenter. In this manner, the laser beam will now be in the center of thetarget zone. This serves as a calibration for the user and insures thatthe laser sighting device is properly aimed.

[0090] A modified version of the laser sighting device of FIG. 11 isillustrated in FIG. 12. Laser sighting device 1100 is shown incombination with an infrared detector 1162 which has an infrared fieldof view 1161. Laser sighting device 1100 includes a laser 1112 whichprojects a laser beam 1114. Laser 1112 is pivotally mounted on pivot1120. A counterbalance 1115 is provided on the side of the laser 1112opposite the pivot 1115. The laser 1112 is powered by power source 1118and adapted to be rotated by motor 1121. Slip rings 1116 are providedfor facilitating the rotation of the laser 1112.

[0091] The laser sighting device 1100 of FIG. 12 is adapted to operatein the same way as sighting device 1000 of FIG. 11. As the laser 1112 isrotated about the pivot point 1120, the laser beam 1114 is projectedagainst the target (not shown) about the periphery of the infrared fieldof view 1161 of the infrared detector 1162.

[0092]FIG. 13 illustrates yet another embodiment of the laser sightingdevice of the present invention. Laser sighting device 1200 is providedas a stand-alone unit which may be mounted on and removed from standardinfrared detectors or radiometers. The sighting device 1200 includes alaser 1212 container within the housing 1201 of the sighting device1200. Laser 1212 is adapted to project a laser beam 1214 against atarget (not shown). The laser 1212 is powered by a power source (notshown). A motor 1221 is connected tot he laser 1212 by rotationalassembly 1227 thereby causing the laser to rotate within the housing1201. A slider 1226 is further provided to facilitate rotation of thelaser 1212 within the housing.

[0093] Adjustment screw 1217 is further provided for controlling theposition of the motor 1221 and, as such, the direction of the laser beam1214. A swivel ball 1222 is provided about the outward end of the laser1212 which is seated in swivel ball seat 1220. Spring washer 1218 isfurther provided adjacent the swivel ball 1222.

[0094] The laser sighting device 1200 operates in substantially the samemanner as the sighting devices depicted in FIGS. 11-12 in that he singlelaser 1212 is rotated by motor 1221 to cause the projecting laser beamto circle around the periphery of an infrared field.

[0095] FIGS. 14-16 illustrate yet another version of the laser sightingdevice of the present invention shown in combination with a radiometer.In the embodiment of FIGS. 14-16, a conventional radiometer 1300 isprovided. The radiometer includes a telescope aiming sight 1305 with alens 1306 mounted on the top thereof. Telescope aiming sight 1305permits the user to aim the radiometer 1300 against a target.

[0096] At least two laser sighting devices 1312 are provided on oppositesides of the radiometer 1300. Device 1312 includes a pair of lasers 1314provided within the laser sighting devices 1312 positioned on each sideof the radiometer approximately 180 degrees apart which are adapted toproject a pair of laser beams (not shown) toward a target on either sideof the energy zone to be measured by the radiometer. In this manner, thelaser beams are used to define the outer periphery of the energy zonebeing measured by the radiometer 1300.

[0097] In an alternate embodiment, the lasers depicted in FIGS. 11-16may be pulsed on and off in a synchronized manner. FIG. 17 depicts theseries of intermittent lines that serve to outline the energy zone insuch an embodiment. The intermittent use of the laser in this embodimentresults in an increase in the efficiency of the laser, which, in turn,allows for an increased concentration of the laser's total wattage in asmaller area, causing a brighter beam.

[0098]FIGS. 18 and 19 illustrate yet another and preferred best modeversion of the laser sighting device of the present invention, incombination with a radiometer. In this embodiment, a conventionalradiometer 1400 is provided. A laser sighting device denoted generallyby reference numeral 1401 has a single-beam laser generator 1402 whichproduces the laser beam 1403. Aligned axially with the laser beam 1403,and in front of the laser generator 1402, there is positioned a support1404 housing a beam splitter, holographic component or a diffractiongrating 1405. In this instance, the diffraction grating 1405 is selectedwhen struck by the laser beam to produce, from the entering single beam1403, a total of twelve sub-division beams 1403 a which aresymmetrically divergent about the axis 1406. Referring to FIG. 19 thereis shown the pattern of laser light spots 1403 b which are formed atindividual mutually spaced locations, where the sub-division beams 1403a strike the target 1407 whose temperature is to be investigated. Due tothe nature of the diffraction grating 1405, the spots 1403 b arecircumferentially equidistantly spaced by distance B in a circle aboutthe axis of the laser beam 1403, and the total spread of thesub-division beams 1403 a is a width A which depends upon the axialdistance of the device from the target 1407. Adjacent to and laterallyof the laser generator 1402 in its support 1404 there is positioned aradiometer 1400 whose viewing axis is parallel to the axis 1406 of thegenerated laser beam, but which may if desired be made adjustable withrespect to the axis 1406 so that a selected area of the target, perhapsnot at the center of the dots 1403 b, may be investigated.

[0099] The apparatus of any one of FIGS. 2,3,4,6,8,11,12,13 and 18 mayfurther include means for projecting a laser beam axially to strike thesurface zone to be measured, e.g. in FIG. 18 the diffraction grating1405 would be selected to provide not only the sub-division beams 1403a, but also a central sub-division beam along the axis 1406.

[0100] Referring to FIG. 20, there is shown schematically a modificationwherein the radiometer 1400 is situated on the central longitudinal axisof the laser generator 1401 and within said plurality of laser beams ata suitable distance downstream of the diffraction grating so as not tointerference with the transmission of the sub-division beams to form thepattern of spots.

[0101] In a practical form of construction, the laser beam generator1401 and the diffraction grating support 1404 and the radiometer wouldconveniently be carried on a support structure, not shown, to provide ahand-held apparatus aimed at a selected area, or areas, to beinvestigated. Thus a method of identifying the extent of a radiationzone on a region whose temperature is to be measured may comprise thesteps of providing a sighting device for use in conjunction with saidradiometer, said device including means for generating a laser beam,splitting said laser beam into a plurality of three or more componentsby passing said beam through or over diffraction grating means, anddirecting said beam components towards said region so as to form aplurality of illuminated areas on said region where said beam componentsimpinge on said region, and determining temperature at said region withsaid radiometer. Preferably, the diffraction grating means is such as tocause the laser beam to be sub-divided into a plurality of three or morebeams which form illuminated areas arranged at intervals on a circle orother closed geometric figure on the region.

[0102] Having thus described the invention with particular reference tothe preferred forms thereof, it will be obvious that various changes andmodifications can be made therein without departing from the spirit andscope of the present invention as defined by the appended claims.

We claim:
 1. A method for outlining an energy zone on a surface whosetemperature is to be measured using a radiometer, said method comprisingthe steps of providing a laser device associated with said radiometer,and causing said device to emit a plurality of at least three laserbeams towards said surface to strike said surface at individual mutuallyspaced locations serving at least to outline said entire energy zone. 2.The method of claim 1, wherein said method further comprises the stepsof causing said sighting device to project a laser beam towards saidsurface, and subdividing said laser beam with a beam splitter means toprovide said more than two of laser beams.
 3. A method for outlining anenergy zone on a surface whose temperature is to be measured using aradiometer, said method comprising the steps of providing a laser deviceassociated with said radiometer, causing said laser device to emit atleast one laser beam, passing said at least one laser beam across adiffraction grating to subdivide said beam into a plurality of at leastthree laser beams, and directing said plurality of at least three laserbeams towards said surface to strike said surface at individual mutuallyspaced locations serving at least to outline said energy zone. 4.Apparatus, for use in conjunction with a radiometer, for outlining anenergy zone on a surface whose temperature is to be measured using saidradiometer, said apparatus comprising; a laser sighting deviceco-operating with said radiometer and means for emitting a plurality ofat least three laser beams to strike said surface at individually spacedapart locations serving to outline said energy zone.
 5. The apparatus ofclaim 4 including a sighting device and a beam splitter diffractionmeans, and wherein said sighting device projects at least one primarylaser beam towards said surface, and wherein beam splitter means aredisposed between said device and said surface to be struck by said atleast one primary laser beam and to subdivide said at least one primarylaser beam into a plurality of secondary laser beams.
 6. Apparatus, foruse in conjunction with a radiometer, for outlining an energy zone on asurface whose temperature is to be measured using said radiometer, saidapparatus comprising a laser sighting device co-operating with saidradiometer, said sighting device projecting at least one primary laserbeam towards said surface, and a diffraction grating disposed betweensaid device and said surface to be struck by said at least one primarylaser beam and to subdivide said laser beam into a plurality of at leastthree secondary laser beams to strike said entire surface atindividually spaced apart locations serving to outline said entireenergy zone.
 7. The apparatus of claim 4 in combination with aradiometer, said radiometer being positioned laterally of said lasersighting device.
 8. The apparatus of claim 4, in combination with aradiometer, said radiometer being positioned between said plurality oflaser beams emitted by said laser sighting device.
 9. The apparatus ofclaim 5 in combination with a radiometer, said radiometer beingpositioned on the central longitudinal axis of said secondary laserbeams downstream of said diffraction means.
 10. A method of measuringand displaying surface temperature in a defined energy zone with aradiation pyrometer comprising:—A) pointing a heat responsive pyrometerin the direction of said energy zone on said surface;—B) directing aplurality of at least three laser beams from a laser generator system toimpinge a plurality of at least three visible spots on said zone toidentify a closed figure which includes most of said zone wheretemperature is to be measured; and—C) locating said pyrometer and saidgenerator as a functional combination to direct said beams inessentially the direction of the pyrometer pointing towards said energyzone so that said spots outline said zone measured by said pyrometer.11. A method of generating beams according to claim 10 in which at leastone beam from said generator is split by a diffraction device. 12.Apparatus for measuring and displaying temperature across a surface inan energy zone comprising: a radiation pyrometer co-operating with alaser beam generator; means directing heat responsive elements of saidpyrometer along a path between said surface and said pyrometer; andmeans directing a plurality of laser beams from said generator along anessentially parallel path to said path between so as to display avisible laser spot pattern around said zone from which said pyrometermeasures temperature.
 13. Apparatus according to claim 12 includingmeans to produce plural laser beams from said generator.
 14. Apparatusaccording to claim 13 in which said means to produce is a diffractiondevice.
 15. A laser sighting device for outlining an energy zone to bemeasured by a radiometer when measuring the temperature of a surface,said device including: means projecting more than two laser beams towardsaid surface; means causing said laser beams to outline the periphery ofsaid energy zone.
 16. A laser sighting device for identifying anddefining an energy zone to by measured by a radiometer when measuringthe temperature of a surface, said device including: means to project atleast one laser beam toward said surface; and means rotating saidprojecting means so as to cause said beam to travel about the peripheryof the energy zone on said surface so as to identify and define theenergy zone.
 17. A laser sighting device for visibly outlining an energyzone to by measured by a radiometer when measuring the temperature of asurface, said device generating more than two laser beams adapted toproject towards said surface on different sides of said energy zone soas to outline substantially the entire periphery thereof.
 18. A lasersighting device for identifying and defining the center and periphery ofan energy zone to be measured by a radiometer when measuring thetemperature of a surface, said device including: means for projectingmore than two laser beams towards said surface; and means for causingsaid laser beams to identify and define both the center andsubstantially the entire periphery of said energy zone.
 19. A lasersighting device for identifying the center of an energy zone on asurface and for outlining the periphery of said energy zone, said deviceadapted to be used in conjunction with a radiometer when measuring thetemperature of said surface, said device including: means for projectingat least one laser beam toward said surface to identify the center ofsaid energy zone; and means for projecting more than two other laserbeams toward said surface to outline the periphery of said energy zoneon said surface.
 20. The laser sighting device of claim 19 wherein saidmeans for projecting said other laser beams is caused to rotate saidother laser beams to travel about and outline the periphery of saidenergy zone on said surface.
 21. Apparatus for use in conjunction with aradiometer for visibly identifying an energy zone on a surface whosetemperature is to by measured using said radiometer, said apparatuscomprising a laser sighting device for emitting laser beams against saidsurface and said beams being positioned to be divergent with respect tothe energy zone to outline visibly the periphery of said zone. 22.Apparatus as claimed in claim 21 wherein said laser sighting deviceemits more than two laser beams against said surface.
 23. Apparatus foruse in conjunction with a radiometer for identifying the extent of anenergy zone whose temperature is to be measured using said radiometer,said apparatus comprising a laser sighting device co-operating with saidradiometer and arranged to emit a laser beam toward said energy zone andmirror means modifying said laser beam and directing said modified beamtowards the energy zone to illuminate a circular line about said energyzone.
 24. Apparatus as claimed in claim 23 wherein said means formodifying and directing said laser beam are mechanical means. 25.Apparatus for use in conjunction with a radiometer for identifying theextent of an energy zone whose temperature is to be measured using saidradiometer, said apparatus comprising a laser sighting deviceco-operating with said radiometer and arranged to emit a circular beamalong the axis of the radiometer towards the energy zone to form anilluminated ring at said energy zone defining the extent of the zone tobe measured.
 26. Apparatus for use in conjunction with a radiometer foridentifying the extent of an energy zone whose temperature is to bemeasured using said radiometer, said apparatus comprising a lasersighting device co-operating with said radiometer for emitting laserbeams toward said energy zone to mark the edge and the center of an areaof said zone which is to be measured.
 27. Apparatus for use inconjunction with a radiometer for visibly outlining an energy zone on asurface whose temperature is to be measured using said radiometer, saidapparatus comprising a laser sighting device for emitting more than twolaser beams against said surface and means for positioning said laserbeams about the energy zone to outline visibly the periphery of saidenergy zone.
 28. Apparatus as claimed in claim 27 wherein said means forpositioning said laser beams are arranged to outline visibly only theperiphery of said energy zone.
 29. Apparatus, as claimed in claim 28wherein said means for positioning said laser beams comprises a mirror,and means for positioning said mirror for receiving and reflecting saidlaser beams against said surface to outline said energy zone.
 30. Amethod for identifying the extent of a radiation zone on a region whosetemperature is to be measured, using a radiometer, said methodcomprising the steps of: providing a sighting device for use inconjunction with said radiometer, said device including means forgenerating a laser beam; splitting said laser beam into more than twocomponents; and directing said components toward said region to identifysubstantially the entire extent of said radiation zone.
 31. A method foridentifying the extent of a radiation zone on an area whose temperatureis to be measured using a radiometer, said method comprising the stepsof: providing a sighting device for use in conjunction With saidradiometer, said device including means for generating a laser beam;splitting said laser beam into more than two components, and directingsaid components toward said area to identify the extent of saidradiation zone.
 32. A method of visibly outlining an energy zone on asurface whose temperature is to be measured using a radiometer, saidmethod comprising the steps of: providing a sighting device for use inconjunction with said radiometer, said device including means forgenerating a laser beam; splitting said laser beam into more than twosplit laser lines; and directing said laser lines towards said surfaceto outline visibly the periphery of said entire energy zone.
 33. Amethod for identifying an energy zone whose temperature is to bemeasured using a radiometer, said method comprising the steps of:providing a sighting device for use in conjunction with said radiometer,said device including means for generating laser beams; splitting saidlaser beams into split laser lines; directing said laser lines towardssaid zone; and positioning said laser lines to identify the periphery ofsaid entire zone.
 34. A method for visibly outlining an energy zone on asurface whose temperature is to be measured using a radiometer, saidmethod comprising the steps of: providing a sighting device means foruse in conjunction with said radiometer, said device including means forgenerating a laser beam; splitting said laser beam into more than twosplit laser lines; directing said laser lines toward said surface, andpositioning said laser lines to outline visibly the periphery of saidzone.
 35. The method of claim 34, wherein said split laser linesidentify the extent of said energy zone.
 36. Apparatus for use inconjunction with a radiometer for identifying a radiation zone in anarea whose temperature is to be measured using said radiometer, saidapparatus comprising a laser sighting device for use in conjunction withsaid radiometer, said laser sighting device including: means forgenerating a laser beam; means for splitting said laser beam into morethan two components; and means for positioning said components toidentify the extent of said entire radiation zone.
 37. Apparatus for usein conjunction with a radiometer for visibly outlining an energy zone ona surface whose temperature is to be measured using said radiometer,said apparatus comprising a laser sighting device for use in conjunctionwith said radiometer, said laser sighting device including: means forgenerating a laser beam; means for splitting said laser beam into morethan two split laser lines; and means for directing said laser linestowards said surface; and means for positioning said laser lines tooutline visibly the periphery of said energy zone.
 38. Apparatus for usein conjunction with a radiometer for identifying the extent of an energyzone whose temperature is to be measured using said radiometer, saidapparatus comprising a laser sighting device co-operating with saidradiometer for emitting more than two laser beams toward said energyzone along separate paths; and means for adjusting said paths of saidlaser beams to outline the periphery of said zone.
 39. Apparatus formeasuring the intensity of detected radiation comprising: a radiationdetector having means for measuring the intensity of said detectedradiation; a laser sighting device for directing more than two laserbeams along axes in the direction of the radiation to be detected todefine the limits of the zone of radiation to be measured; and means forintegrating the detected radiation intensity measurement and the zone ofradiation as defined by the laser beams.
 40. A method for identifying anenergy zone whose temperature is to be measured using a radiometer, saidmethod comprising the steps of: providing a laser sighting device;causing said sighting device to emit more than two laser beams towardsaid surface along separate paths; adjusting said paths of said laserbeams to outline visibly the periphery of said energy zone. 41.Apparatus for identifying an energy zone whose temperature is to bemeasured using a radiometer, said apparatus including: a laser sightingdevice for emitting more than two laser beams toward said surface; andmeans for adjusting said laser beams to outline visibly the periphery ofsaid energy zone.
 42. In apparatus for temperature measurementcomprising: a) a detector responsive to infrared radiation from anenergy zone on a surface to be measured, b) an optical system directingsaid radiation from said energy zone onto said detector, c) and asighting device for ascertaining the position and size of the energyzone on said surface to by measured, by visible laser light, theimprovement in which: d) the sighting device includes a beam splitterelement for production of more than two laser beams outlining visiblythe periphery of substantially said entire zone and for spreading thelaser light intensity.
 43. In a laser sighting device for visiblyoutlining an energy zone to by measured by a radiometer when measuringthe temperature of a surface, including means projecting more than twolaser beams toward said surface, the improvement comprising meanscausing said laser beams to strike the periphery of said zone andvisibly outlining said entire zone.
 44. A device according to claim 43including means projecting at least one laser beam to identify thecenter of said zone.
 45. A temperature measurement device comprising adetector for receiving heat radiation from a measuring zone of theobject under examination, and a direction finder sighting deviceincluding a laser generator providing a laser beam serving as a lightsource, said sighting device further including a holographic beamsplitter providing sub-divisional laser beams to strike the object andshow thereon at least three illuminated areas at the periphery of andenclosing and defining the measuring zone.